Fin-based field effect transistors (FINFETs) are vertical transistor devices in which a semiconductor fin is located on a substrate and is used to define the source, drain, and channel regions of the device. The gate structure overlies the fin in the channel area, and in some configurations multiple fins may be used to provide a multi-gate transistor architecture. The multiple gates may be controlled by a single gate electrode, where the multiple gate surfaces act electrically as a single gate, or by independent gate electrodes.
One example FINFET device is disclosed in U.S. Pat. No. 8,310,013 to Lin et al. The FINFET device includes a substrate of a crystalline semiconductor material having a top surface of a first crystal plane orientation, a fin structure of the crystalline semiconductor material overlying the substrate, a gate structure over a portion of the fin structure, and an epitaxial layer over another portion of the fin structure. The epitaxial layer has a surface with a second crystal plane orientation. The epitaxial layer and underlying fin structure include a source and drain region. The source region is separated from the drain region by the gate structure. A channel is defined in the fin structure from the source region to the drain region, and aligned in a direction parallel to both the surface of the epitaxial layer and the top surface of the substrate. Despite the existence of such configurations, further enhancements in FINFET devices may be desirable in some applications, particularly next generation devices with relatively small dimensions.
Another approach to a FINFET device 200 is shown in FIG. 1. The FINFET device 200 includes a substrate 205, a dielectric layer 206 on the substrate, and first and second fins 202a-202b on the dielectric layer. The FINFET device 200 includes a semiconductor layer 201a-201b around the first and second fins 202a-202b, and a pair of gate stack layers 203-204.